The present invention relates to a knife and a sharpening holder by which the blade of the knife is guided at a predetermined angle with respect to the surface of a sharpening hone when it is being sharpened.
U.S. Pat. Nos. 3,654,823 and 3,800,632 to Juranitch describe and show two-part blade holders that are clamped to the blade of a knife and have a guide bar or flange on each part that bears against the surface of a sharpening hone when the knife is sharpened and maintains the blade at the same angle to the surface of the hone as sharpening progresses. The Juranitch patents are hereby incorporated by reference into the present document for all purposes.
The holders of the Juranitch patents, and holders based on the designs disclosed in the Juranitch patent that are commercially available, are intended to be used interchangeably on different knives. To attach them, the user installs the holder on the blade by positioning the holder on the blade at a specified distance between the cutting edge of the blade and the tip of the clamping portion of the holder with the aid of a ruler or other measuring implement. While the ability to use a Juranitch holder on different knives has the advantage of allowing a user to sharpen several knives with the aid of the same holder, there is a disadvantage to a universal, adjustable holder that is designed to be used with different knives. The disadvantage has two aspects.
One aspect is that it is virtually impossible to install a Juranitch holder on a given knife that is about to be sharpened in the same position on the knife in which it was installed the last time that it was sharpened--the distance between the guide edges of the flange and the cutting edge of the knife blade may be different--the position of the holder lengthwise of the blade may also be different--the holder may be at slightly different angle (cocked) relative to the blade. Even if the difference in the position of the holder from the last sharpening of a particular knife is small, sharpening nonetheless requires grinding a new edge with a different angle to the surface of the blade and removing a relatively large amount of blade material. Consequently, sharpening takes a relatively long time, and each sharpening reduces the life of the blade.
Another aspect of the disadvantage of a universal holder is that if the holder is used to sharpen several knives between the time that a given knife was previously sharpened and the time of resharpening of that knife, the configuration of the holder may have changed due to grinding away of some of the guide edges of the holder parts. Some users push the holder hard against the sharpening hone, thus removing material from the guide edges of the holder parts at about the same rate as from the cutting edge of the knife being sharpened. Therefore, even assuming that the holder is installed on a given knife in a position precisely the same as the position during the last sharpening of the particular knife, any change in the holder has the same effect as a change in the position of the knife in the holder--requiring a lot of honing to establish a slightly different angle of the cutting edge from that produced in the previous sharpening.